D Nut Hole Punch

L

langus480

Member
Hello all,


Making progress on the 1931 Pickup I recently purchased. I have the cab off the frame and replacing the floor channels/ cross brases when I discovered there are D Nuts for the wooden floor board and rivets.


I want to find a D Nut Hole Punch tool, but I need to know what exactly the size D Nuts are offered in the catalogs, as McMasters is pretty pricy to just guess


https://www.mcmaster.com/products/d-shape-knockout-punches/?s=d-shape-knockout-punches


Also, does anyone have a drawing or any information that is specific about rivet sizes for these cross brace pieces?
 
langus480 said:
Hello all,


Making progress on the 1931 Pickup I recently purchased. I have the cab off the frame and replacing the floor channels/ cross brases when I discovered there are D Nuts for the wooden floor board and rivets.


I want to find a D Nut Hole Punch tool, but I need to know what exactly the size D Nuts are offered in the catalogs, as McMasters is pretty pricy to just guess


https://www.mcmaster.com/products/d-shape-knockout-punches/?s=d-shape-knockout-punches


Also, does anyone have a drawing or any information that is specific about rivet sizes for these cross brace pieces?
Click to expand...

I do not have a drawing for these, but I did have a D-shaped punch however they are a PIA to index (-which is what broke mine). The easiest way is to drill or punch the hole and then add a drop of weld in the edge of the hole to form a D shape. Just clamp a piece of brass/copper underneath and use the weld to fill. The bigger issue in doing what this task is you need a die press to be able to dimple the Cross Sill before you punch the hole. I will try to post a picture of mine later.
 
From the looks of the illustration for the McMaster Carr punches, they are a different shape. The Model A "D" nuts only have a small area of flat for the diameter of the hole. I have always done them the hard way. I compass the circle on the known center line then straight edge the flat for size in the original location. I use a single flute step drill to enlarge the starter hole then grind & file the aperture to fit the D-nut going in. I go for as tight a fit as I can get prior to setting the D-nut.

To fabricate the die it takes to punch an aperture of that shape would take a special broach to get it right. Not impossible but the equipment to do it is expensive. The die and the punch have to have hardened edges to use them on thick sheet metal such as is common to the model A in the places where they were used. The aperture shape is common to key lock cylinders but they are generally a larger size.
 
For the minimal amount required, you’ll be best served to follow Brent’s info.
Unless you’re doing many, you won’t recoup the outlay.
Also, you need to decide what actual machine/ punch will do the job and then seek the actual punch.
I have them but the punch fits a 5 ton foot punch; therefore not real portable. You bring the job to the punch; not the punch to the job
 
All great advice, and I realize now how much work and effort there is in punching a "D" hole...


Here's my thought, to cut out the original "D" nuts from the damaged section and weld them into the cross pieces.



Thoughts?
 
langus480 said:
All great advice, and I realize now how much work and effort there is in punching a "D" hole...


Here's my thought, to cut out the original "D" nuts from the damaged section and weld them into the cross pieces.



Thoughts?
Click to expand...

Well, if that's what you want to do. It is not what I would do, but just know that you must dimple the sill so the floorboard sits flat against the sill's ledge. If you don't, the floorboard does not seal and the 'undercarriage fumes & smells' will enter the cabin.
 
Make templates from card-stock of the various size D-Nuts you need to install. Tape the template in place & use a marking pen to transfer the shape onto the body. Drill an under-size diameter hole through the shape, then use a router bit in a Dremel type tool to finish the shape.
You can weld, solder or clinch the D-Nuts into place.
 
I would drill a hole (the diameter of the D from the flat side to the opposite side), then take a rat tail (tapered round) file, (the diameter of the wide part of the D), grind a flat on one side to make a "D" file, then file out the hole.
 
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